/*
 Copyright 2021 The Matrix.org Foundation C.I.C.
 Copyright 2022 Arseny Uskov

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
import ICanvasEffect from '../ICanvasEffect';
import { arrayFastClone } from "../../utils/arrays";

export type HeartOptions = {
    /**
     * The maximum number of hearts to render at a given time
     */
    maxCount: number;
    /**
     * The amount of gravity to apply to the hearts
     */
    gravity: number;
    /**
     * The maximum amount of drift (horizontal sway) to apply to the hearts. Each heart varies.
     */
    maxDrift: number;
    /**
     * The maximum amount of tilt to apply to the heart. Each heart varies.
     */
    maxRot: number;
};

type Heart = {
    x: number;
    y: number;
    xCol: number;
    scale: number;
    maximumDrift: number;
    maximumRot: number;
    gravity: number;
    color: string;
};

export const DefaultOptions: HeartOptions = {
    maxCount: 120,
    gravity: 3.2,
    maxDrift: 5,
    maxRot: 5,
};

const KEY_FRAME_INTERVAL = 15; // 15ms, roughly

export default class Hearts implements ICanvasEffect {
    private readonly options: HeartOptions;

    constructor(options: { [key: string]: any }) {
        this.options = { ...DefaultOptions, ...options };
    }

    private context: CanvasRenderingContext2D | null = null;
    private particles: Array<Heart> = [];
    private lastAnimationTime: number;

    private colours = [
        'rgba(194,210,224,1)',
        'rgba(235,214,219,1)',
        'rgba(255,211,45,1)',
        'rgba(255,190,174,1)',
        'rgba(255,173,226,1)',
        'rgba(242,114,171,1)',
        'rgba(228,55,116,1)',
        'rgba(255,86,130,1)',
        'rgba(244,36,57,1)',
        'rgba(247,126,157,1)',
        'rgba(243,142,140,1)',
        'rgba(252,116,183,1)'];

    public isRunning: boolean;

    public start = async (canvas: HTMLCanvasElement, timeout = 3000) => {
        if (!canvas) {
            return;
        }
        this.context = canvas.getContext('2d');
        this.particles = [];
        const count = this.options.maxCount;
        while (this.particles.length < count) {
            this.particles.push(this.resetParticle({} as Heart, canvas.width, canvas.height));
        }
        this.isRunning = true;
        requestAnimationFrame(this.renderLoop);
        if (timeout) {
            window.setTimeout(this.stop, timeout);
        }
    };

    public stop = async () => {
        this.isRunning = false;
    };

    private resetParticle = (particle: Heart, width: number, height: number): Heart => {
        particle.color = this.colours[(Math.random() * this.colours.length) | 0];
        particle.x = Math.random() * width;
        particle.y = Math.random() * height + height;
        particle.xCol = particle.x;
        particle.scale = (Math.random() * 0.07) + 0.04;
        particle.maximumDrift = (Math.random() * this.options.maxDrift) + 3.5;
        particle.maximumRot = (Math.random() * this.options.maxRot) + 3.5;
        particle.gravity = this.options.gravity + (Math.random() * 4.8);
        return particle;
    };

    private renderLoop = (): void => {
        if (!this.context || !this.context.canvas) {
            return;
        }
        if (this.particles.length === 0) {
            this.context.clearRect(0, 0, this.context.canvas.width, this.context.canvas.height);
        } else {
            const timeDelta = Date.now() - this.lastAnimationTime;
            if (timeDelta >= KEY_FRAME_INTERVAL || !this.lastAnimationTime) {
                // Clear the screen first
                this.context.clearRect(0, 0, this.context.canvas.width, this.context.canvas.height);

                this.lastAnimationTime = Date.now();
                this.animateAndRenderHearts();
            }
            requestAnimationFrame(this.renderLoop);
        }
    };

    private animateAndRenderHearts() {
        if (!this.context || !this.context.canvas) {
            return;
        }
        for (const particle of arrayFastClone(this.particles)) {
            particle.y -= particle.gravity;

            // We treat the drift as a sine function to have a more fluid-like movement instead
            // of a pong-like movement off walls of the X column. This means that for
            // $x=A\sin(\frac{2\pi}{P}y)$ we use the `maximumDrift` as the amplitude (A) and a
            // large multiplier to create a very long waveform through P.
            const peakDistance = 75 * particle.maximumDrift;
            const PI2 = Math.PI * 2;
            particle.x = 6 * particle.maximumDrift * Math.sin(0.7 * (PI2 / peakDistance) * particle.y);
            particle.x += particle.xCol; // bring the particle to the right place

            const posScale = 1 / particle.scale;
            const x = particle.x * posScale;
            const y = particle.y * posScale;

            this.context.save();
            this.context.scale(particle.scale, particle.scale);
            this.context.beginPath();

            // Rotate the heart about its centre.
            // The tilt of the heart is modelled similarly to its horizontal drift,
            // using a sine function.
            this.context.translate(248 + x, 215 + y);
            this.context.rotate((1 / 10) * particle.maximumRot * Math.sin((PI2 / peakDistance) * particle.y * 0.8));
            this.context.translate(-248 - x, -215 - y);

            // Use bezier curves to draw a heart using pre-calculated coordinates.
            this.context.moveTo(140 + x, 20 + y);
            this.context.bezierCurveTo(73 + x, 20 + y, 20 + x, 74 + y, 20 + x, 140 + y);
            this.context.bezierCurveTo(20 + x, 275 + y, 156 + x, 310 + y, 248 + x, 443 + y);
            this.context.bezierCurveTo(336 + x, 311 + y, 477 + x, 270 + y, 477 + x, 140 + y);
            this.context.bezierCurveTo(477 + x, 74 + y, 423 + x, 20 + y, 357 + x, 20 + y);
            this.context.bezierCurveTo(309 + x, 20 + y, 267 + x, 48 + y, 248 + x, 89 + y);
            this.context.bezierCurveTo(229 + x, 48 + y, 188 + x, 20 + y, 140 + x, 20 + y);
            this.context.closePath();

            this.context.fillStyle = particle.color;
            this.context.fill();

            this.context.restore();

            // Remove any dead hearts after a 100px wide margin.
            if (particle.y < -100) {
                const idx = this.particles.indexOf(particle);
                this.particles.splice(idx, 1);
            }
        }
    }
}
